Poorly controlled anger is a common problem with often devastating effects in veterans who have served in a warzone. Adverse consequences include increased risk for divorce, domestic violence, job loss and instability, and other serious impairments in family, social, and occupational functioning. Recent evidence indicates that anger and aggression are likely to be problems for a significant proportion of veterans of Iraq (Operation Iraqi Freedom, OIF; Operation New Dawn, OND) and Afghanistan (Operation Enduring Freedom, OEF). A survey of reintegration problems among 754 OEF/OIF combat veterans receiving VA Medical care showed that anger was the most commonly reported problem, with 57% reporting increased problems in controlling anger. Despite encouraging evidence for efficacy of cognitive behavioral interventions in treating anger in civilian samples, much less is known about the efficacy of such treatments for anger problems in military personnel following exposure to war zone trauma. Promising preliminary findings for individually based cognitive behavioral treatment have been reported, and there is evidence that a group anger management treatment delivered by teleconferencing is as effective as the same treatment delivered in person, but to date there is not a single adequately powered randomized trial designed to test the efficacy of an anger treatment compared to an active control condition in veterans. Building on findings from our randomized pilot study, the objective of the current proposal is to conduct a randomized clinical trial with sufficient statistical power to test the effectiveness of a manualized cognitive behavioal intervention (CBI) that has been adapted from an existing treatment (Anger Control Therapy; Novaco, 1994, 2001) for the treatment of anger problems in OEF/OIF/OND veterans, compared to a manualized supportive therapy intervention (SI) control condition. One hundred and twenty OEF/OIF/OND veterans reporting significant problems with anger will be randomized to receive 12 individual sessions of one of the two study conditions. Outcomes including measures of anger and aggression; interpersonal, social and occupational functioning; and quality of life will be assessed during and at the end of treatment and at 3 and 6 month follow-ups. Exploratory analyses will examine 1) whether a diagnosis of PTSD impacts treatment effectiveness and 2) potential mediators of treatment outcome with CBI.